1. Field of the Invention
The present invention is directed to dispensers or sprayers, and more particularly to dispensers and sprayers provided with a venting system. More specifically, the present invention is directed to a dispenser or sprayer having three bores which is provided with a vent system in one of the bores.
2. Discussion of Background and Material Information
A common problem with liquid spraying devices of the hand-operated type is the need for relief of the negative pressure or vacuum created in the closed container on which the device is used as liquid is pumped. The vacuum created is relieved by venting atmospheric air into the container to displace the liquid dispensed.
One manner of accomplishing this venting of atmospheric air into a container is merely to place a hole in the container to allow air from the outside to enter. A major disadvantage with this simple solution is that the contents of the container can easily spill out through this hole when the sprayer is tilted at an angle or carelessly handled. Moreover, even a small hole in the container, would permit the contents of the container to evaporate.
Various solutions to this simple manner of venting have been proposed in the art, and, in general, usually involve separate or discrete valve means with or without a vent passage, and more often than not, are difficult to construct and are expensive. In addition, prior art devices are often cumbersome to use and operate.
In designing a vent mechanism for permitting outside air to enter a container during spraying, it is important that the container/sprayer combination not leak when the trigger or actuator is at rest, and when the container and sprayer are laid on a side or inverted such as might be the case in normal use in spraying or in shipment where a full container might be supplied with an attached spraying device.
A number of patents have been issued on trigger-piston type hand sprayers useful for dispersing liquids from containers. For example, U.S. Pat. No. 4,072,252 to Emile B. STEYNS et al. discloses a hand operated sprayer with an automatic container vent mechanism. To accomplish the automatic venting in the hand sprayer taught in this patent, the seals on a piston are caused to pass beyond a vent opening leading to the interior of the container when the trigger is pulled. Further reference is made to U.S. Pat. No. 4,072,252 for its description of various solutions to the venting problem.
Japanese Utility Patent No. 52-11686, which issued on Mar. 15, 1977, discloses a hand operated sprayer in which the spray outlet and valves are incorporated into a main piston that moves in a first bore. The ventilation piston is connected to the main piston and moves in a second bore. The ventilation piston slides to the rear of increasingly smaller diameters of the second bore.
U.S. Pat. Nos. 3,897,006, 4,153,203, 4,230,277 and 4,350,298 to TADA disclose hand operated sprayers in which a rod depresses a portion of elastic packing to separate the portion from the housing to allow air to pass into the container. A torsion spring biases the trigger to the non-pumping position in U.S. Pat. Nos. 4,153,203, 4,230,277, and 4,350,298.
U.S. Pat. Nos. 3,797,749, 3,913,841, and 3,701,478 to TADA, 4,558,821 to TADA et al. and Design Patent Nos. 240,036, 241,543, 242,351, 243,333, and 256,271 to TADA are all directed to other types of hand operated sprayers.
The vent system as described below can be adapted to be used with any of the above types of sprayers.